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Science  09 Mar 2007:
Vol. 315, Issue 5817, pp. 1339b
DOI: 10.1126/science.315.5817.1339b

The diversity of plankton in lakes is surprisingly high, and even an apparently uniform-looking body of lake water can offer many ecological niches, depending on the scale of the ebb and flow of water masses, nutrients, temperature gradients, and so on. Huisman et al. have now shown that changing degrees of light penetration also provide niches. In a study ranging from the open ocean to landlocked ponds, the authors found that red picoplankton (absorbing green light) dominate in clear blue waters and green types (absorbing red light) dominate in peaty brown turbid lakes. A model for competition between red- and green-light-absorbing picocyanobacteria in different light fields correctly mirrored nature: Along a gradient of increasing turbidity, red picoplankton are replaced by green, and where turbidity is intermediate, both types of picoplankton can coexist. Moreover, changes in the population density of the plankton itself will affect light absorbance and result in competitive exclusion of the reds by the greens. — CA

Ecol. Lett., in press.

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